Transmission/reception method for mtc apparatus

ABSTRACT

In one aspect, the present specification discloses a transmission/reception method in a machine type communication (MTC) apparatus. The transmission/reception method for the MTC apparatus may comprise the steps of: receiving information about the specific number of a bundle of downlink control channels which are receivable on a plurality of downlink subframes; and determining the location of the downlink subframe in which the specific-number bundle of downlink control channels can finish reception in accordance with time division duplex (TDD) uplink/downlink setting. Here, when the reception about the bundle of downlink control channels is not finished at the location of the determined downlink subframe, it can be assumed that the reception of the bundle of downlink control channels will continue up to the location of the fastest downlink subframe in which the specific-number bundle of downlink control channels can finish reception among the subframes according to the TDD method.

FIELD OF THE INVENTION

The present invention relates to mobile communication.

RELATED ART

3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) thatis an advancement of UMTS (Universal Mobile Telecommunication System) isbeing introduced with 3GPP release 8. In 3GPP LTE, OFDMA (orthogonalfrequency division multiple access) is used for downlink, and SC-FDMA(single carrier-frequency division multiple access) is used for uplink.The 3GPP LTE adopts MIMO (multiple input multiple output) having maximumfour antennas. Recently, a discussion of 3GPP LTE-A (LTE-Advanced) whichis the evolution of the 3GPP LTE is in progress.

As set forth in 3GPP TS 36.211 V10.4.0, the physical channels in 3GPPLTE may be classified into data channels such as PDSCH (physicaldownlink shared channel) and PUSCH (physical uplink shared channel) andcontrol channels such as PDCCH (physical downlink control channel),PCFICH (physical control format indicator channel), PHICH (physicalhybrid-ARQ indicator channel) and PUCCH (physical uplink controlchannel).

Meanwhile, in recent years, communication, i.e., machine typecommunication (MTC), occurring between devices or between a device and aserver without a human interaction, i.e., a human intervention, isactively under research. The MTC refers to the concept of communicationbased on an existing wireless communication network used by a machinedevice instead of a user equipment (UE) used by a user.

Since the MTC has a feature different from that of a normal UE, aservice optimized to the MTC may differ from a service optimized tohuman-to-human communication. In comparison with a current mobilenetwork communication service, the MTC can be characterized as adifferent market scenario, data communication, less costs and efforts, apotentially great number of MTC apparatuses, wide service areas, lowtraffic for each MTC apparatus, etc.

Recently, it is considered to extend cell coverage of a BS for an MTCapparatus, and various schemes for extending the cell coverage are underdiscussion. However, when the cell coverage is extended, if the BStransmits a channel to the MTC apparatus located in the coverageextension region as if transmitting a channel to a normal UE, the MTCapparatus has a difficulty in receiving the channel.

Further, as the MTC apparatus is expected to have low performance inorder to supply more MTC apparatuses at a low price, if the BS transmitsa PDCCH or a PDSCH to the MTC apparatus located in the coverageextension region as if transmitting a PDCCH or a PDSCH to a normal UE,the MTC apparatus has a difficulty in receiving the PDCCH or the PDSCH.

SUMMARY OF THE INVENTION

Accordingly, the disclosure of the specification has been made in aneffort to solve the problem.

To achieve the foregoing purpose, when a machine-type (MTC) apparatus islocated in a coverage extension region of a base station (BS), the BSmay repeatedly transmit PDCCHs or PDSCHs (that is, transmit a bundle ofPDCCHs or PDSCHs) on a plurality of subframes.

However, repeatedly transmitting PDCCHs or PDSCHs (that is, transmittinga bundle of PDCCHs or PDSCHs) on a plurality of subframes may cause aproblem to PUCCH/PUSCH transmission timings.

To solve such a problem, an embodiment of the present invention providesa transmission and reception method of a machine-type communication(MTC) apparatus. The method may comprise: receiving information on aspecific number of downlink control channels which are bundled andreceivable on a plurality of downlink subframes; and determining aposition of a downlink subframe in which reception of the bundle of thespecific number of downlink control channels is to be finished accordingto a time division duplex (TDD) uplink/downlink configuration. Whenreception of the bundle of downlink control channels is not finished atthe position of the determined downlink subframe, it is assumed thatreception of the bundle of downlink control channels continues up to aposition of an earliest downlink subframe in which reception of thebundle of the specific number of downlink control channels is finishedamong TDD based subframes.

The method may further comprise: determining a position of a subframefor transmitting an uplink channel based on the position of the earliestdownlink subframe when reception of the bundle of PDCCHs continues overthe position of the determined downlink subframe.

The uplink channel may comprise a physical uplink control channel(PUCCH) or physical uplink shared channel (PUSCH). The control channelsmay be a physical downlink control channel (PDCCH).

Positions of downlink subframes in which reception of the bundle of thespecific number of downlink control channels may be finished areexpressed in a table according to the TDD uplink/downlink configuration.

To solve the foregoing problem, an embodiment of the present inventionprovides a machine-type communication (MTC) apparatus. The MTC apparatusmay comprise: a transceiver to receive information on a specific numberof downlink control channels which are bundled and receivable on aplurality of downlink subframes; and a processor to control thetransceiver to determine a position of a downlink subframe in whichreception of the bundle of the specific number of downlink controlchannels is to be finished according to a time division duplex (TDD)uplink/downlink configuration. Here, when reception of the bundle ofdownlink control channels is not finished at the position of thedetermined downlink subframe, the processor assumes that reception ofthe bundle of downlink control channels continues up to a position of anearliest downlink subframe in which reception of the bundle of thespecific number of downlink control channels is finished among TDD basedsubframes.

According to the disclosure of the present specification, the problem ofthe foregoing conventional technology is solved. More specifically,according to the disclosure of the present specification, the receptionperformance and decoding performance of a machine-type communication(MTC) apparatus located in a coverage extension region of a base stationmay be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system.

FIG. 2 illustrates the architecture of a radio frame according tofrequency division duplex (FDD) of 3rd generation partnership project(3GPP) long term evolution (LTE).

FIG. 3 illustrates the architecture of a downlink radio frame accordingto time division duplex (TDD) in 3GPP LTE.

FIG. 4 illustrates an example resource grid for one uplink or downlinkslot in 3GPP LTE.

FIG. 5 illustrates the architecture of a downlink subframe.

FIG. 6 illustrates the architecture of an uplink subframe in 3GPP LTE.

FIG. 7 illustrates an example of comparison between a single carriersystem and a carrier aggregation system.

FIG. 8 exemplifies cross-carrier scheduling in a carrier aggregationsystem.

FIG. 9 illustrates an example of transmitting system information.

FIG. 10a illustrates an example of machine-type communication (MTC).

FIG. 10b illustrates an example of cell coverage extension for an MTCapparatus.

FIG. 11 illustrates an example of a time interval between a PDCCH bundleand a PUCCH bundle including an ACK/NACK of the PDCCH bundle.

FIG. 12 illustrates an example of a time interval between a PDCCH bundleand a PUSCH bundle.

FIG. 13 illustrates an example of positions of subframes fortransmitting a PDSCH bundle in a TDD environment.

FIG. 14 illustrates another example of positions of subframes fortransmitting a PUSCH bundle in the TDD environment.

FIG. 15 is a block diagram illustrating a wireless communication systemaccording to an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, based on 3rd Generation Partnership Project (3GPP) longterm evolution (LTE) or 3GPP LTE-advanced (LTE-A), the present inventionwill be applied. This is just an example, and the present invention maybe applied to various wireless communication systems. Hereinafter, LTEincludes LTE and/or LTE-A.

The technical terms used herein are used to merely describe specificembodiments and should not be construed as limiting the presentinvention. Further, the technical terms used herein should be, unlessdefined otherwise, interpreted as having meanings generally understoodby those skilled in the art but not too broadly or too narrowly.Further, the technical terms used herein, which are determined not toexactly represent the spirit of the invention, should be replaced by orunderstood by such technical terms as being able to be exactlyunderstood by those skilled in the art. Further, the general terms usedherein should be interpreted in the context as defined in thedictionary, but not in an excessively narrowed manner.

The expression of the singular number in the specification includes themeaning of the plural number unless the meaning of the singular numberis definitely different from that of the plural number in the context.In the following description, the term ‘include’ or ‘have’ may representthe existence of a feature, a number, a step, an operation, a component,a part or the combination thereof described in the specification, andmay not exclude the existence or addition of another feature, anothernumber, another step, another operation, another component, another partor the combination thereof.

The terms “first” and “second” are used for the purpose of explanationabout various components, and the components are not limited to theterms “first” and “second.” The terms “first” and “second” are only usedto distinguish one component from another component. For example, afirst component may be named as a second component without deviatingfrom the scope of the present invention.

It will be understood that when an element or layer is referred to asbeing “connected” to or “coupled to” another element or layer, it can bedirectly connected or coupled to the other element or layer orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly connected to” or “directlycoupled to” another element or layer, there are no intervening elementsor layers present.

Hereinafter, exemplary embodiments of the present invention will bedescribed in greater detail with reference to the accompanying drawings.In describing the present invention, for ease of understanding, the samereference numerals are used to denote the same components throughout thedrawings, and repetitive description on the same components will beomitted. Detailed description on well-known arts which are determined tomake the gist of the invention unclear will be omitted. The accompanyingdrawings are provided to merely make the spirit of the invention readilyunderstood, but not should be intended to be limiting of the invention.It should be understood that the spirit of the invention may be expandedto its modifications, replacements or equivalents in addition to what isshown in the drawings.

As used herein, “base station” generally refers to a fixed station thatcommunicates with a wireless device and may be denoted by other termssuch as eNB (evolved-NodeB), BTS (base transceiver system), or accesspoint.

As used herein, user equipment (UE) may be stationary or mobile, and maybe denoted by other terms such as device, wireless device, terminal, MS(mobile station), UT (user terminal), SS (subscriber station), MT(mobile terminal) and etc.

FIG. 1 shows a wireless communication system.

Referring to FIG. 1, the wireless communication system includes at leastone base station (BS) 20. Respective BSs 20 provide a communicationservice to particular geographical areas 20 a, 20 b, and 20 c (which aregenerally called cells).

The UE generally belongs to one cell and the cell to which the terminalbelongs is referred to as a serving cell. A base station that providesthe communication service to the serving cell is referred to as aserving BS. Since the wireless communication system is a cellularsystem, another cell that neighbors to the serving cell is present.Another cell which neighbors to the serving cell is referred to aneighbor cell. A base station that provides the communication service tothe neighbor cell is referred to as a neighbor BS. The serving cell andthe neighbor cell are relatively decided based on the UE.

Hereinafter, a downlink means communication from the base station 20 tothe terminal 10 and an uplink means communication from the terminal 10to the base station 20. In the downlink, a transmitter may be a part ofthe base station 20 and a receiver may be a part of the terminal 10. Inthe uplink, the transmitter may be a part of the terminal 10 and thereceiver may be a part of the base station 20.

Meanwhile, the wireless communication system may be any one of amultiple-input multiple-output (MIMO) system, a multiple-inputsingle-output (MISO) system, a single-input single-output (SISO) system,and a single-input multiple-output (SIMO) system. The MIMO system uses aplurality of transmit antennas and a plurality of receive antennas. TheMISO system uses a plurality of transmit antennas and one receiveantenna. The SISO system uses one transmit antenna and one receiveantenna. The SIMO system uses one transmit antenna and one receiveantenna. Hereinafter, the transmit antenna means a physical or logicalantenna used to transmit one signal or stream and the receive antennameans a physical or logical antenna used to receive one signal orstream.

Meanwhile, the wireless communication system may be generally dividedinto a frequency division duplex (FDD) type and a time division duplex(TDD) type. According to the FDD type, uplink transmission and downlinktransmission are achieved while occupying different frequency bands.According to the TDD type, the uplink transmission and the downlinktransmission are achieved at different time while occupying the samefrequency band. A channel response of the TDD type is substantiallyreciprocal. This means that a downlink channel response and an uplinkchannel response are approximately the same as each other in a givenfrequency area. Accordingly, in the TDD based wireless communicationsystem, the downlink channel response may be acquired from the uplinkchannel response. In the TDD type, since an entire frequency band istime-divided in the uplink transmission and the downlink transmission,the downlink transmission by the base station and the uplinktransmission by the terminal may not be performed simultaneously. In theTDD system in which the uplink transmission and the downlinktransmission are divided by the unit of a subframe, the uplinktransmission and the downlink transmission are performed in differentsubframes.

Hereinafter, the LTE system will be described in detail.

FIG. 2 shows a downlink radio frame structure according to FDD of 3rdgeneration partnership project (3GPP) long term evolution (LTE).

The radio frame of FIG. 2 may be found in the section 5 of 3GPP TS36.211 V10.4.0 (2011-12) “Evolved Universal Terrestrial Radio Access(E-UTRA); Physical Channels and Modulation (Release 10)”.

Referring to FIG. 2, the radio frame consists of 10 subframes. Onesubframe consists of two slots. Slots included in the radio frame arenumbered with slot numbers 0 to 19. A time required to transmit onesubframe is defined as a transmission time interval (TTI). The TTI maybe a scheduling unit for data transmission. For example, one radio framemay have a length of 10 milliseconds (ms), one subframe may have alength of 1 ms, and one slot may have a length of 0.5 ms.

The structure of the radio frame is for exemplary purposes only, andthus the number of subframes included in the radio frame or the numberof slots included in the subframe may change variously.

Meanwhile, one slot may include a plurality of OFDM symbols. The numberof OFDM symbols included in one slot may vary depending on a cyclicprefix (CP).

FIG. 3 shows an example of a resource grid for one uplink or downlinkslot in 3GPP LTE.

For this, 3GPP TS 36.211 V10.4.0 (2011-12) “Evolved UniversalTerrestrial Radio Access (E-UTRA); Physical Channels and Modulation(Release 8)”, Ch. 4 may be referenced, and this is for TDD (timedivision duplex).

The radio frame includes 10 sub-frames indexed 0 to 9. One sub-frameincludes two consecutive slots. The time for one sub-frame to betransmitted is denoted TTI (transmission time interval). For example,the length of one sub-frame may be 1 ms, and the length of one slot maybe 0.5 ms.

One slot may include a plurality of OFDM (orthogonal frequency divisionmultiplexing) symbols in the time domain. The OFDM symbol is merely torepresent one symbol period in the time domain since 3GPP LTE adoptsOFDMA (orthogonal frequency division multiple access) for downlink (DL),and thus, the multiple access scheme or name is not limited thereto. Forexample, OFDM symbol may be denoted by other terms such as SC-FDMA(single carrier-frequency division multiple access) symbol or symbolperiod.

By way of example, one slot includes seven OFDM symbols. However, thenumber of OFDM symbols included in one slot may vary depending on thelength of CP (cyclic prefix). According to 3GPP TS 36.211 V8.7.0, oneslot, in the normal CP, includes seven OFDM symbols, and in the extendedCP, includes six OFDM symbols.

Resource block (RB) is a resource allocation unit and includes aplurality of sub-carriers in one slot. For example, if one slot includesseven OFDM symbols in the time domain and the resource block includes 12sub-carriers in the frequency domain, one resource block may include7×12 resource elements (REs).

Sub-frames having index #1 and index #6 are denoted special sub-frames,and include a DwPTS (Downlink Pilot Time Slot:DwPTS), a GP (GuardPeriod) and an UpPTS (Uplink Pilot Time Slot). The DwPTS is used forinitial cell search, synchronization, or channel estimation in aterminal. The UpPTS is used for channel estimation in the base stationand for establishing uplink transmission sync of the terminal. The GP isa period for removing interference that arises on uplink due to amulti-path delay of a downlink signal between uplink and downlink.

In TDD, a DL (downlink) sub-frame and a UL (Uplink) co-exist in oneradio frame. Table 1 shows an example of configuration of a radio frame.

TABLE 1 UL-DL Configu- Switch-point Subframe index raiton periodicity 01 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5 ms D S U U D D S U U D2 5 ms D S U D D D S U D D 3 10 ms  D S U U U D D D D D 4 10 ms  D S U UD D D D D D 5 10 ms  D S U D D D D D D D 6 5 ms D S U U U D S U U D

‘D’ denotes a DL sub-frame, ‘U’ a UL sub-frame, and ‘S’ a specialsub-frame. When receiving a UL-DL configuration from the base station,the terminal may be aware of whether a sub-frame is a DL sub-frame or aUL sub-frame according to the configuration of the radio frame.

The DL (downlink) sub-frame is split into a control region and a dataregion in the time domain. The control region includes up to three firstOFDM symbols in the first slot of the sub-frame. However, the number ofOFDM symbols included in the control region may be changed. A PDCCH andother control channels are assigned to the control region, and a PDSCHis assigned to the data region.

FIG. 4 illustrates an example resource grid for one uplink or downlinkslot in 3GPP LTE.

Referring to FIG. 4, the uplink slot includes a plurality of OFDM(orthogonal frequency division multiplexing) symbols in the time domainand NRB resource blocks (RBs) in the frequency domain. For example, inthe LTE system, the number of resource blocks (RBs), i. e., NRB, may beone from 6 to 110.

Here, by way of example, one resource block includes 7×12 resourceelements that consist of seven OFDM symbols in the time domain and 12sub-carriers in the frequency domain. However, the number ofsub-carriers in the resource block and the number of OFDM symbols arenot limited thereto. The number of OFDM symbols in the resource block orthe number of sub-carriers may be changed variously. In other words, thenumber of OFDM symbols may be varied depending on the above-describedlength of CP. In particular, 3GPP LTE defines one slot as having sevenOFDM symbols in the case of CP and six OFDM symbols in the case ofextended CP.

OFDM symbol is to represent one symbol period, and depending on system,may also be denoted SC-FDMA symbol, OFDM symbol, or symbol period. Theresource block is a unit of resource allocation and includes a pluralityof sub-carriers in the frequency domain. The number of resource blocksincluded in the uplink slot, i.e., NUL, is dependent upon an uplinktransmission bandwidth set in a cell. Each element on the resource gridis denoted resource element.

Meanwhile, the number of sub-carriers in one OFDM symbol may be one of128, 256, 512, 1024, 1536, and 2048.

In 3GPP LTE, the resource grid for one uplink slot shown in FIG. 4 mayalso apply to the resource grid for the downlink slot.

FIG. 5 illustrates the architecture of a downlink sub-frame.

In FIG. 5, assuming the normal CP, one slot includes seven OFDM symbols,by way of example. However, the number of OFDM symbols included in oneslot may vary depending on the length of CP (cyclic prefix). That is, asdescribed above, according to 3GPP TS 36.211 V 10.4.0, one slot includesseven OFDM symbols in the normal CP and six OFDM symbols in the extendedCP.

Resource block (RB) is a unit for resource allocation and includes aplurality of sub-carriers in one slot. For example, if one slot includesseven OFDM symbols in the time domain and the resource block includes 12sub-carriers in the frequency domain, one resource block may include7×12 resource elements (REs).

The DL (downlink) sub-frame is split into a control region and a dataregion in the time domain. The control region includes up to first threeOFDM symbols in the first slot of the sub-frame. However, the number ofOFDM symbols included in the control region may be changed. A PDCCH(physical downlink control channel) and other control channels areassigned to the control region, and a PDSCH is assigned to the dataregion.

The physical channels in 3GPP LTE may be classified into data channelssuch as PDSCH (physical downlink shared channel) and PUSCH (physicaluplink shared channel) and control channels such as PDCCH (physicaldownlink control channel), PCFICH (physical control format indicatorchannel), PHICH (physical hybrid-ARQ indicator channel) and PUCCH(physical uplink control channel).

The PCFICH transmitted in the first OFDM symbol of the sub-frame carriesCIF (control format indicator) regarding the number (i.e., size of thecontrol region) of OFDM symbols used for transmission of controlchannels in the sub-frame. The wireless device first receives the CIF onthe PCFICH and then monitors the PDCCH.

Unlike the PDCCH, the PCFICH is transmitted through a fixed PCFICHresource in the sub-frame without using blind decoding.

The PHICH carries an ACK (positive-acknowledgement)/NACK(negative-acknowledgement) signal for a UL HARQ (hybrid automatic repeatrequest). The ACK/NACK signal for UL (uplink) data on the PUSCHtransmitted by the wireless device is sent on the PHICH.

The PBCH (physical broadcast channel) is transmitted in the first fourOFDM symbols in the second slot of the first sub-frame of the radioframe. The PBCH carries system information necessary for the wirelessdevice to communicate with the base station, and the system informationtransmitted through the PBCH is denoted MIB (master information block).In comparison, system information transmitted on the PDSCH indicated bythe PDCCH is denoted SIB (system information block).

The PDCCH may carry activation of VoIP (voice over internet protocol)and a set of transmission power control commands for individual UEs insome UE group, resource allocation of an higher layer control messagesuch as a random access response transmitted on the PDSCH, systeminformation on DL-SCH, paging information on PCH, resource allocationinformation of UL-SCH (uplink shared channel), and resource allocationand transmission format of DL-SCH (downlink-shared channel). A pluralityof PDCCHs may be sent in the control region, and the terminal maymonitor the plurality of PDCCHs. The PDCCH is transmitted on one CCE(control channel element) or aggregation of some consecutive CCEs. TheCCE is a logical allocation unit used for providing a coding rate perradio channel's state to the PDCCH. The CCE corresponds to a pluralityof resource element groups. Depending on the relationship between thenumber of CCEs and coding rates provided by the CCEs, the format of thePDCCH and the possible number of PDCCHs are determined.

The control information transmitted through the PDCCH is denoteddownlink control information (DCI). The DCI may include resourceallocation of PDSCH (this is also referred to as DL (downlink) grant),resource allocation of PUSCH (this is also referred to as UL (uplink)grant), a set of transmission power control commands for individual UEsin some UE group, and/or activation of VoIP (Voice over InternetProtocol).

The base station determines a PDCCH format according to the DCI to besent to the terminal and adds a CRC (cyclic redundancy check) to controlinformation. The CRC is masked with a unique identifier (RNTI; radionetwork temporary identifier) depending on the owner or purpose of thePDCCH. In case the PDCCH is for a specific terminal, the terminal'sunique identifier, such as C-RNTI (cell-RNTI), may be masked to the CRC.Or, if the PDCCH is for a paging message, a paging indicator, forexample, P-RNTI (paging-RNTI) may be masked to the CRC. If the PDCCH isfor a system information block (SIB), a system information identifier,SI-RNTI (system information-RNTI), may be masked to the CRC. In order toindicate a random access response that is a response to the terminal'stransmission of a random access preamble, an RA-RNTI (randomaccess-RNTI) may be masked to the CRC.

In 3GPP LTE, blind decoding is used for detecting a PDCCH. The blinddecoding is a scheme of identifying whether a PDCCH is its own controlchannel by demasking a desired identifier to the CRC (cyclic redundancycheck) of a received PDCCH (this is referred to as candidate PDCCH) andchecking a CRC error. The base station determines a PDCCH formataccording to the DCI to be sent to the wireless device, then adds a CRCto the DCI, and masks a unique identifier (this is referred to as RNTI(radio network temporary identifier) to the CRC depending on the owneror purpose of the PDCCH.

The uplink channels include a PUSCH, a PUCCH, an SRS (Sounding ReferenceSignal), and a PRACH (physical random access channel).

FIG. 6 illustrates the architecture of an uplink sub-frame in 3GPP LTE.

Referring to FIG. 6, the uplink sub-frame may be separated into acontrol region and a data region in the frequency domain. The controlregion is assigned a PUCCH (physical uplink control channel) fortransmission of uplink control information. The data region is assigneda PUSCH (physical uplink shared channel) for transmission of data (insome cases, control information may also be transmitted).

The PUCCH for one terminal is assigned in resource block (RB) pair inthe sub-frame. The resource blocks in the resource block pair take updifferent sub-carriers in each of the first and second slots. Thefrequency occupied by the resource blocks in the resource block pairassigned to the PUCCH is varied with respect to a slot boundary. This isreferred to as the RB pair assigned to the PUCCH having beenfrequency-hopped at the slot boundary.

The terminal may obtain a frequency diversity gain by transmittinguplink control information through different sub-carriers over time. mis a location index that indicates a logical frequency domain locationof a resource block pair assigned to the PUCCH in the sub-frame.

The uplink control information transmitted on the PUCCH includes an HARQ(hybrid automatic repeat request), an ACK (acknowledgement)/NACK(non-acknowledgement), a CQI (channel quality indicator) indicating adownlink channel state, and an SR (scheduling request) that is an uplinkradio resource allocation request.

The PUSCH is mapped with a UL-SCH that is a transport channel. Theuplink data transmitted on the PUSCH may be a transport block that is adata block for the UL-SCH transmitted for the TTI. The transport blockmay be user information. Or, the uplink data may be multiplexed data.The multiplexed data may be data obtained by multiplexing the transportblock for the UL-SCH and control information. For example, the controlinformation multiplexed with the data may include a CQI, a PMI(precoding matrix indicator), an HARQ, and an RI (rank indicator). Or,the uplink data may consist only of control information.

A carrier aggregation system is now described.

FIG. 7 illustrates an example of comparison between a single carriersystem and a carrier aggregation system.

Referring to FIG. 7, there may be various carrier bandwidths, and onecarrier is assigned to the terminal. On the contrary, in the carrieraggregation (CA) system, a plurality of component carriers (DL CC A toC, UL CC A to C) may be assigned to the terminal. Component carrier (CC)means the carrier used in then carrier aggregation system and may bebriefly referred as carrier. For example, three 20 MHz componentcarriers may be assigned so as to allocate a 60 MHz bandwidth to theterminal.

Carrier aggregation systems may be classified into a contiguous carrieraggregation system in which aggregated carriers are contiguous and anon-contiguous carrier aggregation system in which aggregated carriersare spaced apart from each other. Hereinafter, when simply referring toa carrier aggregation system, it should be understood as including boththe case where the component carrier is contiguous and the case wherethe control channel is non-contiguous.

When one or more component carriers are aggregated, the componentcarriers may use the bandwidth adopted in the existing system forbackward compatibility with the existing system. For example, the 3GPPLTE system supports bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHzand 20 MHz, and the 3GPP LTE-A system may configure a broad band of 20MHz or more only using the bandwidths of the 3GPP LTE system. Or, ratherthan using the bandwidths of the existing system, new bandwidths may bedefined to configure a wide band.

The system frequency band of a wireless communication system isseparated into a plurality of carrier frequencies. Here, the carrierfrequency means the cell frequency of a cell. Hereinafter, the cell maymean a downlink frequency resource and an uplink frequency resource. Or,the cell may refer to a combination of a downlink frequency resource andan optional uplink frequency resource. Further, in the general easewhere carrier aggregation (CA) is not in consideration, one cell mayalways have a pair of an uplink frequency resource and a downlinkfrequency resource.

In order for packet data to be transmitted/received through a specificcell, the terminal should first complete a configuration on the specificcell. Here, the configuration means that reception of system informationnecessary for data transmission/reception on a cell is complete. Forexample, the configuration may include an overall process of receivingcommon physical layer parameters or MAC (media access control) layersnecessary for data transmission and reception or parameters necessaryfor a specific operation in the RRC layer. A configuration-complete cellis in the state where, once when receiving information indicating packetdata may be transmitted, packet transmission and reception may beimmediately possible.

The cell that is in the configuration complete state may be left in anactivation or deactivation state. Here, the “activation” means that datatransmission or reception is being conducted or is in ready state. Theterminal may monitor or receive a control channel (PDCCH) and a datachannel (PDSCH) of the activated cell in order to identify resources(possibly frequency or time) assigned thereto.

The “deactivation” means that transmission or reception of traffic datais impossible while measurement or transmission/reception of minimalinformation is possible. The terminal may receive system information(SI) necessary for receiving packets from the deactivated cell. Incontrast, the terminal does not monitor or receive a control channel(PDCCH) and data channel (PDSCH) of the deactivated cell in order toidentify resources (probably frequency or time) assigned thereto.

Cells may be classified into primary cells and secondary cells, servingcells.

The primary cell means a cell operating at a primary frequency. Theprimary cell is a cell where the terminal conducts an initial connectionestablishment procedure or connection re-establishment procedure withthe base station or is a cell designated as a primary cell during thecourse of handover.

The secondary cell means a cell operating at a secondary frequency. Thesecondary cell is configured once an RRC connection is established andis used to provide an additional radio resource.

The serving cell is configured as a primary cell in case no carrieraggregation is configured or when the terminal cannot offer carrieraggregation. In case carrier aggregation is configured, the term“serving cell” denotes a cell configured to the terminal and a pluralityof serving cells may be included. One serving cell may consist of onedownlink component carrier or a pair of {downlink component carrier,uplink component carrier}. A plurality of serving cells may consist of aprimary cell and one or more of all the secondary cells.

As described above, the carrier aggregation system, unlike the singlecarrier system, may support a plurality of component carriers (CCs),i.e., a plurality of serving cells.

Such carrier aggregation system may support cross-carrier scheduling.The cross-carrier scheduling is a scheduling scheme that may conductresource allocation of a PUSCH transmitted through other componentcarriers than the component carrier basically linked to a specificcomponent carrier and/or resource allocation of a PDSCH transmittedthrough other component carriers through a PDCCH transmitted through thespecific component carrier. In other words, the PDCCH and the PDSCH maybe transmitted through different downlink CCs, and the PUSCH may betransmitted through an uplink CC other than the uplink CC linked to thedownlink CC where the PDCCH including a UL grant is transmitted. Assuch, the system supporting cross-carrier scheduling needs a carrierindicator indicating a DL CC/UL CC through which a PDSCH/PUSCH istransmitted where the PDCCH offers control information. The fieldincluding such carrier indicator is hereinafter denoted carrierindication field (CIF).

The carrier aggregation system supporting cross-carrier scheduling maycontain a carrier indication field (CIF) in the conventional DCI(downlink control information) format. In the cross-carrierscheduling-supportive carrier aggregation system, for example, an LTE-Asystem, may have 3 bits expanded due to addition of the CIF to theexisting DCI format (i.e., the DCI format used in the LTE system), andthe PDCCH architecture may reuse the existing coding method or resourceallocation method (i.e., CCE-based resource mapping).

FIG. 8 exemplifies cross-carrier scheduling in the carrier aggregationsystem.

Referring to FIG. 8, the base station may configure a PDCCH monitoringDL CC (monitoring CC) set. The PDCCH monitoring DL CC set consists ofsome of all of the aggregated DL CCs, and if cross-carrier scheduling isconfigured, the user equipment performs PDCCH monitoring/decoding onlyon the DL CCs included in the PDCCH monitoring DL CC set. In otherwords, the base station transmits a PDCCH for PDSCH/PUSCH that issubject to scheduling only through the DL CCs included in the PDCCHmonitoring DL CC set. The PDCCH monitoring DL CC set may be configuredUE-specifically, UE group-specifically, or cell-specifically.

FIG. 8 illustrates an example in which three DL CCs (DL CC A, DL CC B,and DL CC C) are aggregated, and DL CC A is set as a PDCCH monitoring DLCC. The user equipment may receive a DL grant for the PDSCH of DL CC A,DL CC B, and DL CC C through the PDCCH of DL CC A. The DCI transmittedthrough the PDCCH of DL CC A contains a CIF so that it may indicatewhich DL CC the DCI is for.

FIG. 9 illustrates an example of transmitting system information.

System information is classified into a master information block (MIB)and a plurality of system information blocks (SIB). The MIB includes themost important physical layer information on a cell. The SIBs includesdifferent types. A first type of SIB includes information used toevaluate whether a UE is allowed to access a cell and schedulinginformation on another type of SIB. A second type of SIB (SIB type 2)includes information on common and shared channels. A third type of SIB(SIB type 3) includes cell reselection information related mostly to aserving cell. A fourth type of SIB (SIB type 4) includes frequencyinformation on a serving cell and intra-frequency information on aneighbor cell related to cell reselection. A fifth type of SIB (SIB type5) includes information on another E-UTRA frequency and inter-frequencyinformation on a neighbor cell related to cell reselection. A sixth typeof SIB (SIB type 6) includes information on a UTRA frequency andinformation on a UTRA neighbor cell related to cell reselection. Aseventh type of SIB (SIB type 7) includes information on a GERANfrequency related to cell reselection.

As shown in FIG. 9, the MIB is transmitted to a UE 10 via a PBCH. Thefirst type of SIB (SIB type 1) is mapped to a DL-SCH and transmitted tothe UE 10 via a PDSCH. Other types of SIBs are transmitted to the UE viaa PDSCH through a system information message.

Hereinafter, MTC will be described.

FIG. 10a illustrates an example of machine type communication (MTC).

The MTC refers to information exchange performed between MTC apparatuses100 via a BS 200 without human interactions or information exchangeperformed between the MTC apparatus 100 and an MTC server 700 via theBS.

The MTC server 700 is an entity for communicating with the MTC apparatus100. The MTC server 700 executes an MTC application, and provides anMTC-specific service to the MTC apparatus.

The MTC apparatus 100 is a wireless device for providing the MTC, andmay be fixed or mobile.

A service provided using the MTC is differentiated from an existingcommunication service requiring human intervention, and its servicerange is various, such as tracking, metering, payment, medical fieldservices, remote controlling, etc. More specifically, examples of theservice provided using the MTC may include reading a meter, measuring awater level, utilizing a surveillance camera, inventory reporting of avending machine, etc.

The MTC apparatus is characterized in that a transmission data amount issmall and uplink/downlink data transmission/reception occurs sometimes.Therefore, it is effective to decrease a unit cost of the MTC apparatusand to decrease battery consumption according to a low data transmissionrate. The MTC apparatus is characterized of having a small mobility, andthus is characterized in that a channel environment does almost notchange.

FIG. 10b illustrates an example of cell coverage extension for an MTCapparatus.

Recently, it is considered to extend cell coverage of a BS for an MTCapparatus 100, and various schemes for extending the cell coverage areunder discussion.

However, when the cell coverage is extended, if the BS transmits a PDSCHand a PDCCH including scheduling information for the PDSCH to the MTCapparatus located in the coverage extension region as if it istransmitted to a normal UE, the MTC apparatus has a difficulty inreceiving them.

Embodiments of the Present Invention

Thus, embodiments of the present invention are provided to solve theforegoing problem.

According to an embodiment of the present invention, to solve theforegoing problem, when a BS transmits a PDSCH and PDCCH to an MTCapparatus 100 located in a coverage extension region, the BS repeatedlytransmits the PDSCH and PDCCH on a plurality of subframes (for example,a bundle of subframes). Thus, the MTC apparatus receives a bundle ofPDCCHs through the plurality of subframes and decode the bundle ofPDCCHs, thereby increasing decoding success rate. That is, the MTCapparatus may decode a portion or all of the PDCCHs in the bundlereceived through a plurality of subframes, thereby successfully decodingPDCCHs. Likewise, the MTC apparatus receives a bundle of PDSCHs througha plurality of subframes and decodes a portion or all of PDSCHs in thebundle, thereby increasing decoding success rate.

Similarly, the MTC apparatus located in the coverage extension regionmay transmit a bundle of PUCCHs through a plurality of subframes. Also,the MTC apparatus may transmit a bundle of PUSCHs through a plurality ofsubframes.

However, when PDSCHs and PDCCHs are repeatedly transmitted on aplurality of subframes as described above, there may arise problems intransmission timings of ACKs/NACKs of the PDSCHs (for example,transmission timing of a PUCCH including an ACK/NACK) and intransmission timing of PUSCHs. Further, there may arise problems indetermining a subframe for transmitting an ACK/NACK after receiving aPDCCI-I and in determining a subframe for transmitting a PUSCH.

Thus, solutions to such problems will be described below.

(A) Solution to Problem in Transmission Timings of ACK/NACK of PDSCH

As described above, an MTC apparatus located in a coverage extensionregion may transmit a bundle of PUCCHs including an ACK/NACK of areceived PDSCH on a plurality of subframes. When the bundle of PUCCHs istransmitted through the plurality of subframes, a BS decodes all or aportion of the PUCCHs in the bundle received on the plurality ofsubframes, thereby increasing decoding success rate.

As shown in FIG. 11, the BS may transmit a bundle of PDSCHs to an MTCapparatus on D subframes. The MTC apparatus successfully receiving thePDSCHs through the D subframes may transmit a PUCCH or PUSCH includingan ACK/NACK of the PDSCHs on A subframes.

Here, the MTC apparatus may need to determine a timing for transmittingthe ACK/NACK. Transmission timings are described in FDD and TDD,respectively.

First, an FDD case is described as follows.

In an FDD environment, as shown in FIG. 11 defining a last subframeamong the subframes transmitting the bundle of PDSCHs as ‘subframe n,’the bundle of PUCCHs/PUSCHs including the ACK/NACK may be transmittedthrough from ‘subframe n+G.’

Here, G may be, for example, 4. For instance, when transmission of thebundle of PDSCHs is finished at ‘subframe n,’ the MTC apparatus maytransmit the bundle of PUCCHs/PUSCHs including the ACK/NACK of thePDSCHs to the BS through from ‘subframe n+4.’

Next, a TDD ease is described as follows.

In a TDD environment, subframes for uplink transmission and subframesfor downlink transmission are designated in Table 1. Therefore, whentransmission of the bundle of PDSCHs is finished at ‘subframe n’ and theMTC apparatus starts transmitting the bundle of PUCCHs/PUSCHs includingthe ACK/NACK from ‘subframe n+G,’ G may not be a constant value.

Thus, in the TDD environment, when transmission of the bundle of PDSCHsis finished at ‘subframe n,’ the MTC apparatus may start transmittingthe bundle of PUCCHs/PUSCHs including the ACK/NACK through from a firstavailable subframe for uplink transmission among subframes subsequent to‘subframe n+4.’ For example, according to UL-DL configuration 1illustrated in Table 1, when transmission of the bundle of PDSCHs isfinished at subframe 0, the MTC apparatus may start transmitting thebundle of PUCCHs/PUSCHs including the ACK/NACK at subframe 7, which is afirst available subframe for uplink transmission, among subframessubsequent to subframe 4.

Alternatively, in the TDD environment, when transmission of the bundleof PDSCHs is finished at ‘subframe n’ and the MTC apparatus transmitsthe bundle of PUCCHs/PUSCHs including the ACK/NACK through a pluralityof subframes from ‘subframe n+G,’ it is suggested in the presentinvention to determine G as in Table 2 considering the positions ofdownlink subframes, uplink subframes and special subframes in order toevenly distribute subframe resources for transmitting the PUCCHs/PUSCHs.

Table 2 illustrates G according to a UL-DL configuration when definingthe position of a subframe at which transmission of the bundle of PDSCHsis finished as ‘subframe n.’ For example, in the use of UL-DLconfiguration 2 in Table 1, when transmission of the bundle of PDSCHs isfinished at subframe 5, G is 7 according to Table 2. Thus, the MTCapparatus starts transmitting the PUCCHs/PUSCHs including the ACK/NACKfrom subframe 12, which is seven subframes apart from subframe 5.

TABLE 2 UL-DL Subframe n (last subframe for transmitting PDSCH bundle)configuration 0 1 2 3 4 5 6 7 8 9 0 4 6 — — — 4 6 — — — 1 7 6 — — 4 7 6— — 4 2 7 6 — 4 8 7 6 — 4 8 3 4 11 — — — 7 6 6 5 5 4 12 11 — — 8 7 7 6 54 5 12 11 — 9 8 7 6 5 4 13 6 7 7 — — — 7 7 — — 5

(B) Solution to PUSCH Transmission Timing Problem

An MTC apparatus located in a coverage extension region may repeatedlyreceive a bundle of PDCCHs including an uplink grant on a plurality ofsubframes and transmit a bundle of PUSCHs on a plurality of subframesthrough an uplink resource indicated by the uplink grant.

For example, as shown in FIG. 12, a BS transmits a bundle of PDCCHsincluding an uplink grant to the MTC apparatus through C subframes, theMTC apparatus may transmit a bundle of PUSCHs on U subframes accordingto the uplink grant.

Here, it is needed to determine transmission timings for the bundle ofPDCCHs and the bundle of PUSCHs. Transmission timings are described inFDD and TDD, respectively.

First, an FDD case is described as follows.

In an FDD environment, as shown in FIG. 12, defining the position of asubframe at which transmission of the bundle of PDCCHs is finished as‘subframe n,’ the bundle of PUSCHs related to the PDCCHs may betransmitted through from ‘subframe n+K.’

In the FDD environment, K may be, for example, 4. That is, whentransmission of the bundle of PDCCHs is finished at ‘subframe n,’ theMTC apparatus may transmit the bundle of PUSCHs related to the PDCCHsthrough a plurality of subframes from ‘subframe n+4.’

Next, a TDD case is described as follows.

In a TDD environment, subframes for uplink transmission and subframesfor downlink transmission are designated in Table 1. Therefore, whentransmission of the bundle of PDSCHs is finished at ‘subframe n’ and theMTC apparatus starts transmitting the bundle of PUSCHs from ‘subframen+K,’ K may not be a constant value.

Thus, in the TDD environment, when transmission of the bundle of PDSCHsis finished at ‘subframe n,’ the MTC apparatus may start transmittingthe bundle of PUSCHs through from a first available subframe for uplinktransmission among subframes subsequent to ‘subframe n+4.’ For example,according to UL-DL configuration 1 illustrated in Table 1, whentransmission of the bundle of PDSCHs is finished at subframe 0, the MTCapparatus may start transmitting the bundle of PUSCHs at subframe 7,which is a first available subframe for uplink transmission, amongsubframes subsequent to subframe 4.

Alternatively, in the TDD environment, when transmission of the bundleof PDSCHs is finished at ‘subframe n’ and the MTC apparatus transmitsthe bundle of PUSCHs through a plurality of subframes from ‘subframen+K,’ it is suggested in the present invention to determine K as inTable 3 considering the positions of downlink subframes, uplinksubframes and special subframes in order to evenly distribute subframeresources for transmitting the PUSCHs.

Table 3 illustrates K according to a UL-DL configuration when definingthe position of a subframe at which transmission of the bundle of PDSCHsis finished as ‘subframe n.’ For example, in the use of UL-DLconfiguration 2 in Table 1, when transmission of the bundle of PDSCHs isfinished at subframe 6, K is 6 according to Table 3. Thus, the MTCapparatus starts transmitting the PUSCHs from subframe 12, which is sixsubframes apart from subframe 6.

TABLE 3 UL-DL Subframe n (last subframe for transmitting PDSCH bundle)configuration 0 1 2 3 4 5 6 7 8 9 0 4 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 44 5 4 6 7 7 7 7 5

Meanwhile, in the TDD environment, when a first PDCCH bundle and asecond PDCCH bundle are transmitted from the BS to the MTC apparatus,there is a possibility that the position of a subframe for transmittinga first PUSCH bundle with respect to the first PDCCH bundle overlap withthe position of a subframe for transmitting a second PUSCH bundle withrespect to the second PDCCH bundle.

Thus, one embodiment of the present invention suggests that the BSfinishes transmitting a PDCCH bundle only on a particular downlinksubframe. Specifically, in the embodiment, the BS finishes transmissionof a PDCCH bundle only at a subframe position illustrated in Table 4according to a UL-DL configuration.

That is, when the BS transmits a PDCCH bundle to the MTC apparatus, theBS may notify in advance the MTC apparatus that PDCCHs are transmittedthrough C subframes. Then, after transmission of the PDCCH bundle isstarted at a particular subframe, the PDCCH bundle may be transmittedduring the C subframes. Here, the position of a subframe at whichtransmission of the PDCCH bundle is finished may be ‘subframe m.’

TABLE 4 Subframe m UL-DL configuration (last subframe for transmittingPDCCH bundle) 0 0, 1, 5, 6 1 1, 4, 6, 9 2 3, 8 3 0, 8, 9 4 8, 9 5 8 6 0,1, 5, 6, 9

However, depending on a situation, transmission of the PDCCH bundle fromthe BS may not actually be finished at a subframe illustrated in Table4. That is, the position of a subframe at which transmission of thePDCCH bundle from the BS is actually finished may be different fromsubframe m illustrated in Table 4. In this case, the MTC apparatus maynot determine an appropriate position of a subframe for startingtransmission of a PUSCH bundle. Hereinafter, a solution to such aproblem is described.

To solve the foregoing problem, one embodiment of the present inventionsuggests that the BS continues transmission of the PDCCH bundle up tothe position of an earliest subframe among values of subframe m,illustrated in Table 4, subsequent to a subframe at which transmissionof the PDCCH bundle is scheduled to be finished. In this case, the MTCapparatus identifies the position of the subframe at which transmissionof the PCDDHs is finished, not the position of the subframe at whichtransmission of the PDCCHs is originally scheduled to be finished, as aPDCCH transmission end subframe.

For example, when UL-DL configuration 3 is used, subframe positionswhere transmission of the PDCCH bundle is originally scheduled to befinished may be 0, 8, and 9. However, when transmission of the PDCCHbundle is actually finished on subframe 3 the BS may continuetransmission of the PDCCH bundle up to subframe 8, which is an earliestsubframe on which transmission of the PDCCH bundle can be finished,among subframes subsequent to subframe 3. Thus, the MTC apparatus mayreceive the PDCCH bundle on up to subframe 8, not up to subframe 3 andrecognize subframe 8 as a PDCCH bundle transmission end subframe.Alternatively, the MTC apparatus may receive the PDCCH bundle on only upto subframe 3 that is a subframe in which reception of the PDCCH bundleis originally scheduled to be finished and assume, as subframe 8, theposition of a subframe in which reception of the PDCCH bundle isfinished, which is needed for calculating the position of a subframe fortransmitting the PUSCH bundle.

(C) Determination of Subframe For Transmitting ACK/NACK of PDSCH

As shown in FIG. 11, a BS may transmit a bundle of PDSCHs to the MTCapparatus on D contiguous or non-contiguous downlink subframes. The MTCapparatus successfully receiving the bundle of PDSCHs through the Dsubframes may transmit PUCCHs or PUSCHs containing an ACK/NACK of thebundle of PDSCHs on A contiguous or non-contiguous downlink subframes.Here, the positions of the subframes transmitting the PDSCHs may betransmitted from the BS to the MTC apparatus through an MIB, SIB, or thelike. For example, the positions of the subframes transmitting thebundle of PDSCHs to the MTC apparatus in a 10-msec radio frame may betransmitted to the MTC apparatus in a bitmap format.

This scheme may also be applied to a TDD system, which is described, forexample, with reference to FIG. 13 as follows.

As shown in FIG. 13, a bundle of PDSCHs may be transmitted to an MTCapparatus located in a coverage extension region on all or a portion ofdownlink subframes. In this case, the positions of the subframesavailable for transmission of the PDSCHs to the MTC apparatus located inthe coverage extension region among the subframes in the 10-msec radioframe may be transmitted to the MTC apparatus using the bitmap format.

Defining the number of subframes for transmitting a bundle of PDSCHs toan MTC apparatus located in a coverage extension region in each 10-msecradio frame as N_(D), the positions of the subframes for transmittingthe bundle of PDSCHs to the MTC apparatus in the 10-msec radio frame maybe represented by D_(i). Here, i may be 0, 1, . . . , N_(D).

TABLE 5 UL-DL D_(i) configuration 0 1 2 3 4 5 6 7 8 9 0 4 6 — — — 4 6 —— — 1 7 6 — — 4 7 6 — — 4 2 7 6 — 4 8 7 6 — 4 8 3 4 11 — — — 7 6 6 5 5 412 11 — — 8 7 7 6 5 4 5 12 11 — 9 8 7 6 5 4 13 6 7 7 — — — 7 7 — — 5

Here, one embodiment of the present invention suggests a method fordetermining the positions of subframes for transmitting ACKs/NACKs ofthe PDSCHs according to the positions of the subframes for transmittingthe bundle of PDSCHs to the MTC apparatus in each 10-msec radio frame.

In this case, defining the number of subframes for the MTC apparatus totransmit an ACK/NACK in each 10-msec radio frame as N_(A), the positionsof the subframes for the MTC apparatus to transmit the ACK/NACK in the10-msec radio frame may be determined according to (D_(i)+G_(i)) mod10.Here, i may be 0, 1, . . . , N_(D).

For instance, one embodiment of the present invention suggests thatG_(i) for determining the positions of subframes for transmittingACKs/NACKs of the PDSCHs depending on the positions of the subframes fortransmitting the bundle of PDSCHs to the MTC apparatus located in thecoverage extension region has a relationship in Table 5. Table 5illustrates G_(i) according to the position D_(i) of a subframe fortransmitting the bundle of PDSCHs in each UL-DL configuration. Accordingto Table 5, for example, when UL-DL configuration 3 is used, since G_(i)related to the position of a PDSCH transmitted through subframe 5 is 7,the position of an ACK/NACK transmission subframe related to theposition of the PDSCH transmitted through subframe 5 is subframe 2,obtained by (5+7) mod 10=2.

According to the suggested operation, for example, in a case of TDDuplink/downlink configuration 2, as shown in FIG. 13, when PDSCHs aretransmitted to the MTC apparatus located in the coverage extensionregion on subframes 3, 4, 8, and 9, the position of a subframe fortransmitting an ACK/NACK of the PDSCHs may be calculated as follows.

The positions of the subframes for transmitting the bundle of PDSCHs maybe expressed as D=3, D₂=4, D₃=8, and D₄=9. Since UL-DL configuration 2is used, G_(i) is obtained from Table 5 such that G1=4, G2=8, G3=4, andG4=8. The positions of subframes for transmitting an ACK/NACK are(D1+G1) mod10=7, (D2+G2) mod10=2, (D3+G3) mod10=2, and (D4+G4) mod10=7.Accordingly, the positions of subframes for the MTC apparatus totransmit an ACK/NACK of the received PDSCHs are subframe 2 and subframe7.

For example, as shown in FIG. 14, after finishing receiving the PDSCHs,the MTC apparatus may start transmission of a PUCCH/PUSCH including anACK/NACK on subframes 2 and 7.

Meanwhile, one embodiment of the present invention suggests anothermethod for transmitting a bundle of PUSCHs/PUSCHs including an ACK/NACKof a bundle of PDSCHs on a plurality of subframes after the MTCapparatus receives the bundle of PDSCHs in the TDD environment. Whentransmission of the bundle of PDSCHs to the MTC apparatus is finished at‘subframe n,’ the MTC apparatus may transmit the bundle of PUCCHs/PUSCHsincluding the ACK/NACK on a plurality of subframes (that is, N_(A)subframes) from ‘subframe n+G.’ Here, the MTC apparatus may transmit thePUCCHs/PUSCHs including the ACK/NACK of the bundle of PDSCHs only on‘subframes n+G*a.’ Here, a may be 0, 1, . . ., N_(A). Here, G may bedetermined according to Table 12.

(D) Determination of Subframe For Transmitting PUSCH

The MTC apparatus located in the coverage extension region may receive abundle of PDCCHs including an uplink grant and then transmit a bundle ofPUSCHs through an uplink resource indicated by the uplink grant.

Here, as described above, the positions of subframes for transmittingthe bundle of PDCCHs may be transmitted through an MIB, SIB, or the likefrom the BS to the MTC apparatus. That is, as described above, thepositions of the subframes for transmitting the bundle of PDCCHs to theMTC apparatus in a 10-msec radio frame may be transmitted to the MTCapparatus in a bitmap format. Particularly, in the TDD environment, itmay be efficient to transmit the positions of the subframes fortransmitting the bundle of PDCCHs to the MTC apparatus in the 10-msecradio frame to the MTC apparatus in the bitmap format. The positions ofthe subframes for transmitting the bundle of PDCCHs are illustrated inTable 6. In particular, it may be very effective to notify the MTCapparatus of the positions of the subframes for transmitting the bundleof PDCCHs including the uplink grant in the bitmap format. Accordingly,the MTC apparatus recognizes that the bundle of PDCCHs including theuplink grant can be received only on the subframes illustrated in Table6, thereby remarkably reducing complexity. Alternatively, the MTCapparatus may use the positions of the subframes illustrated in Table 6only to obtain the positions of subframes for transmitting the PUSCHs.

TABLE 6 Subframe for transmitting TDD UL/DL configuration PDCCH bundleincluding uplink grant 0 0, 1, 5, 6 1 1, 4, 6, 9 2 3, 8 3 0, 8, 9 4 8, 95 8 6 0, 1, 5, 6, 9

Meanwhile, defining the number of subframes for transmitting a bundle ofPDCCHs including an uplink grant to the MTC apparatus in each 10-msecradio frame as N_(C), the positions of the subframes for transmittingthe bundle of PDCCHs including the uplink grant to the MTC apparatuslocated in the coverage extension region in the 10-msec radio frame maybe represented by C_(i). Here, i may be 0, 1, . . ., N_(C).

Here, the present invention suggests determining the positions ofsubframes for transmitting PUSCHs with respect to the PDCCHs (uplinkgrant) according to the positions of the subframes for transmitting thePDCCHs (uplink grant) to the MTC apparatus located in the coverageextension region in each 10-msec radio frame.

In this case, defining the number of subframes in each 10-msec radioframe for the MTC apparatus located in the coverage extension region totransmit PUSCHs as N_(U), the positions of the subframes in the 10-msecradio frame for the MTC apparatus located in the coverage extensionregion to transmit a bundle of PUSCHs may be expressed as (C_(i)+K_(i))mod10. Here, i may be 0, 1, . . ., N_(C). Table 7 illustrates K_(i)according to C_(i). More specifically, Table 7 illustrates K_(i) fordetermining the positions of subframes for the MTC apparatus to transmita bundle of PUSCHs according to the positions of subframes for the MTCapparatus to receive a bundle of PDCCHs including an uplink grant.

TABLE 7 TDD UL/DL C_(i) configuration 0 1 2 3 4 5 6 7 8 9 0 4 6 4 6 1 64 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5

According to Table 7, for example, when UL-DL configuration 1 is used,since K_(i) related to subframe 6 for transmitting a bundle of PDSCHs is6, the position of a subframe for transmitting the bundle of PUSCHs isdetermined by (6+6) mod 10=2.

However, when the subframe C_(i) for transmitting the bundle of PDCCHsincluding the uplink grant is not the position of a subframe illustratedin Table 6, the MTC apparatus may not consider the position of thesubframe in determining a subframe for transmitting a PUSCH.

For example, in the use of UL-DL configuration 1, when the MTC apparatuscan receive a bundle of PDCCHs including an uplink grant on subframes 1,4, and 6, the position of a subframe for transmitting a bundle of PUSCHswith respect to the bundle of PDCCHs may be calculated as follows.First, the positions of the subframes for transmitting the bundle ofPDCCHs may be expressed as C₁=1, C₂=4, and C₃=6. Since UL-DLconfiguration 1 is used, K_(i) is obtained from Table 7 such that K₁=6,K₂=4, and K₃=6. The positions of subframes for the MTC apparatus totransmit the bundle of PUSCHs are (C₁+K₁) mod10=7, (C₂+K₂) mod10=8, and(C₃+K₃) mod10=2. To sum up, the positions of the subframes for the MTCapparatus to transmit the bundle of PUSCHs are subframes 2, 7, and 8.

Meanwhile, one embodiment of the present invention suggests anothermethod for transmitting a bundle of PUSCHs on a plurality of subframesafter the MTC apparatus receives a bundle of PDCCHs including an uplinkgrant in the TDD environment. For example, when the MTC apparatusfinishes transmission of a bundle of PDCCHs at ‘subframe n,’ the MTCapparatus may transmit a bundle of PUSCHs on N_(U) subframes from‘subframe n+K. ’ More specifically, the MTC apparatus may transmit thebundle of PUSCHs on ‘subframes n+K*a.’ Here, a may be 0, 1, . . . ,N_(U), and K may be obtained from Table 3.

The aforementioned embodiments of the present invention can beimplemented through various means. For example, the embodiments of thepresent invention can be implemented in hardware, firmware, software,combination of them, etc. Details thereof will be described withreference to the drawing.

FIG. 15 is a block diagram illustrating a wireless communication systemaccording to an embodiment of the present invention.

The base station (BS) 200/300 includes processor 201/301, memory202/302, and radio frequency (RF) unit 203/303. The memory 202/302coupled with the processor 201/301 stores a variety of information fordriving the processor 201/301. The RF unit 203/303 coupled to theprocessor 201/301 transmits and/or receive radio signals. The processor201/301 implements the proposed functions, procedures, and/or methods.In the aforementioned embodiment, an operation of the BS may beimplemented by the processor 201/301.

The MTC apparatus 100 includes a processor 101, a memory 102, and an RFunit 103. The memory 102 coupled to the processor 101 stores a varietyof information for driving the processor 101. The RF unit 103 coupled tothe processor 101 transmits and/or receives a radio signal. Theprocessor 101 implements the proposed functions, procedure, and/ormethods.

The processor may include an application-specific integrated circuit(ASIC), a separate chipset, a logic circuit, and/or a data processingunit. The memory may include a read-only memory (ROM), a random accessmemory (RAM), a flash memory, a memory card, a storage medium, and/orother equivalent storage devices. The RF unit may include a base-bandcircuit for processing a radio signal. When the embodiment isimplemented in software, the aforementioned methods can be implementedwith a module (i.e., process, function, etc. ) for performing theaforementioned functions. The module may be stored in the memory and maybe performed by the processor. The memory may be located inside oroutside the processor, and may be coupled to the processor by usingvarious well-known means.

Although the aforementioned exemplary system has been described on thebasis of a flowchart in which steps or blocks are listed in sequence,the steps of the present invention are not limited to a certain order.Therefore, a certain step may be performed in a different step or in adifferent order or concurrently with respect to that described above.Further, it will be understood by those ordinary skilled in the art thatthe steps of the flowcharts are not exclusive. Rather, another step maybe included therein or one or more steps may be deleted within the scopeof the present invention.

What is claimed is:
 1. A transmission and reception method of amachine-type communication (MTC) apparatus comprising: receivinginformation on a specific number of downlink control channels which arebundled and receivable on a plurality of downlink subframes; anddetermining a position of a downlink subframe in which reception of thebundle of the specific number of downlink control channels is to befinished according to a time division duplex (TDD) uplink/downlinkconfiguration, wherein when reception of the bundle of downlink controlchannels is not finished at the position of the determined downlinksubframe, it is assumed that reception of the bundle of downlink controlchannels continues up to a position of an earliest downlink subframe inwhich reception of the bundle of the specific number of downlink controlchannels is finished among TDD based subframes.
 2. The of claim 1,further comprising: determining a position of a subframe fortransmitting an uplink channel based on the position of the earliestdownlink subframe when reception of the bundle of PDCCHs continues overthe position of the determined downlink subframe.
 3. The method of claim2, wherein the uplink channel comprises a physical uplink controlchannel (PUCCH) or physical uplink shared channel (PUSCH).
 4. The methodof claim 1, wherein positions of downlink subframes in which receptionof the bundle of the specific number of downlink control channels isfinished are expressed in a table according to the TDD uplink/downlinkconfiguration.
 5. The method of claim 1, wherein positions of downlinksubframes in which reception of the bundle of the specific number ofdownlink control channels is finished are expressed in a tableillustrated below according to the TDD uplink/downlink configuration:Uplink/downlink configuration Position of subframe 0 0, 1, 5, 6 1 1, 4,6, 9 2 3, 8 3 0, 8, 9 4 8, 9 5 8 6 0, 1, 5, 6, 9


6. The method of claim 1, wherein the control channels are a physicaldownlink control channel (PDCCH).
 7. A machine-type communication (MTC)apparatus comprising: a transceiver to receive information on a specificnumber of downlink control channels which are bundled and receivable ona plurality of downlink subframes; and a processor to control thetransceiver to determine a position of a downlink subframe in whichreception of the bundle of the specific number of downlink controlchannels is to be finished according to a time division duplex (TDD)uplink/downlink configuration, wherein when reception of the bundle ofdownlink control channels is not finished at the position of thedetermined downlink subframe, the processor assumes that reception ofthe bundle of downlink control channels continues up to a position of anearliest downlink subframe in which reception of the bundle of thespecific number of downlink control channels is finished among TDD basedsubframes.
 8. The MTC apparatus of claim 7, wherein the processordetermines a position of a subframe for transmitting an uplink channelbased on the position of the earliest downlink subframe when receptionof the bundle of PDCCHs continues over the position of the determineddownlink subframe.
 9. The MTC apparatus of claim 7, wherein the uplinkchannel comprises a physical uplink control channel (PUCCH) or physicaluplink shared channel (PUSCH).
 10. The MTC apparatus of claim 7, whereinpositions of downlink subframes in which reception of the bundle of thespecific number of downlink control channels is finished are expressedin a table according to the TDD uplink/downlink configuration.
 11. TheMTC apparatus of claim 7, wherein the control channels are a physicaldownlink control channel (PDCCH).